![Quote](images/misc/quote_icon.png)
Originally Posted by
DavidEccleston
All Canon cameras have a high-ISO noise reduction option that records with the shutter closed for as long as it recorded with the shutter open, and subtracts the sensor-specific read noise from the actual image data. It's not that it's taking 30 seconds to process the image, it's that it takes 30 seconds to re-create 30 seconds worth of noise.
edit: I'm going to edit... perhaps not *all* Canon cameras have this option. Many do. Perhaps all, but I don't know for sure.